Our Eyes Actually Aren't Good Enough To See In 4K

Cameras and screens are constantly getting better, offering you better resolution, better color, and better features-none-of-us-understand. The goal, always, is to create a picture just as good as what the human eye sees. No one ever tries to create a picture better than what the eye can see since, um, there wouldn't be much point, because you wouldn't be able to see it, right?

So, just how good is your eye? If we're talking resolution—the way a 4k TV looks better than a plain HD one—we're sort of able to answer that. Pretty much all of your eyesight comes thanks to a type of light-sensitive cell in your eye called cones, and you have a fixed number of cones, around six million. Each cone detects just one of three primary colors, so it takes three cones to see the equivalent of one pixel. That means your sight tops out at two million pixels, or two megapixels.

Which sounds impressive enough. Only, your 4k screen blasts out eight megapixels. That's four times as many dots as you're ever able to see.

"No, that's impossible," you feel like saying. "I know I can see my 4k screen. Plus, I can see the ugly wall to the side of the screen, and a light blinking in the corner of my eye, and a dog running along the floor, so I must be able to see much more than 4k." But you can't, not really.

When you look at a screen (or at anything), you don't get a wide view of stuff at all. Most of your cones are concentrated at one tiny part of your eye called the fovea, which lets you at any one moment focus on just a tiny patch of space. Try keeping your eyes completely still, and you'll only be able to read a few words in front of you right now—everything else is a blur.

Your eyes take in more than that, but that's because they constantly dart in all directions, and because your brain fills in the gaps based on what it assumes everything else must be like. So, a 4k TV does look better than some television from 20 years ago—yes, you are able to tell the difference between 4k and HD. But you've only got enough eye power to appreciate it one square inch at a time.

This fact came from the new One Cracked Fact newsletter. Want more like this, straight from your email inbox, without any ads or popups? Join here: